单选题 Paul: Mark, I'm sorry if I've upset you.
Mark: I thought you knew I liked Lucy.
Paul: Yes, but I didn't realize you two were serious.
Mark: I see.
Paul: Believe me, ______
Mark: That's OK.
Paul: Look, I'll phone her and cancel our date tomorrow.
Mark: No, just leave it.
A. I'll let her know for sure. B. I'm really sorry!
C. I'll keep that in mind. D. I'm not going to let her go.